1999 Mazda Protege NO Power Steering

[moparcharger74]

My son has a 1999 Mazda Protege with a Pwr Steering problem I cant figure out. To start with, it had a bad Pwr Steering fluid leak that ended up being a rusted out Pwr Steering Fluid Cooler Line down in front of the radiator. We took the tube / line off and had it repaired at a Tubing Bender shop that does brake and fuel lines. Put it back on, leak fixed, purged air out of system, now we have no Pwr Steering assist at all. Wasn't sure about how to fix so I took it to a Local Mechanic. First he said Pwr Steering Pump has extreamly low pressure, so we put a used Pwr Steering Pump on. Now he said Pwr Steering Pump has plenty of pressure, but still no Pwr Steering pressure assist when you drive it. Next he says that it has to be the Steering Rack / Gear assembly. So we have him to put a used Pwr Steering Rack / Gear on, but to no avail. Still no Pwr Steering assist while driving. Now he is saying that the Pwr Steering Pump has a Power Steering Pump Switch on it that is controlled by the PCM and he thinks that the PCM might have a problem. That is when I said enough and picked the car up to stop the proverbial bleeding. I looked on ALLDATA PRO that a friend has access to look up a schematic of the Electrical systems and I did see the circuit for the Pwr Steering Pump Switch which goes back to a terminal # 31 on the PCM connector, but I could not find a diagram or an explanation on how the Pwr Steering Pump Circuit works. If anyone could help with this problem it would be greatly appreciated. By the way, the Pwr Steering Fluid Resivoir did run extreamly low on Pwr Steering Fluid a couple times while my son was driving before we found the leak in the tube! Thanks again, MOPARCHARGER74

[93gmcjimmy]

the rust you found in the cooling line might be clogging your system. check your lines.

[mrmikey]

The only connection from the power steering sysem to the vehicle electronics is a pressure switch that increases engine idle speed when it senses steering system pressure. You'd have that situation when you're parking for instance.
Like the previous poster said it could be rust in the system. I don't think it would totally plug the system it's more than likely the pressure relief is stuck open with rust or crap. Another possability is the supply hose from the resevoir to the pump could be collapsed internally.
Mind you this is assuming that both used units are good.......Mike

[moparcharger74]

This past weekend we did some more troubleshooting and found a couple more things out. First of all we figured out that like before, we have no power steering at idle, but if we rev the engine up past 2000 RPMs, we have good power steering. Second of all, ALLDATA says to check the continuity of the Power Steering Pump Switch to ground when the steering is straight ahead and also fully turned with the engine running. There should be NO Continuity when straight ahead, and Continuity to ground when fully turned. What we found is NO Continuity at all when Straight Ahead or Fully Turned. Does this mean that the PSP Switch is bad on the used pump that was put on? Also, how does this correlate to the fact that there is good power steering when the engine is rev'ed above 2000 RPMs, or does rev'ing the engine point towards a second problem like a cloged supply hose like you mentioned before? Again, I really appreciate all advice. Thanks to all!

[mrmikey]

Does this mean that the PSP Switch is bad on the used pump that was put on

Yep

Also, how does this correlate to the fact that there is good power steering when the engine is rev'ed above 2000 RPMs

It doesn't, when you rev up the engine you're doing the same thing the switch does, mind you at a lot higher rpm. The switch just bumps up the engine a few hundred rpm.

....or does rev'ing the engine point towards a second problem

Probably, hard to diagnose from a distance tho but it points to the pump. Either the supply is restricted, if it is you should be able to hear the pump cavitating, a whining sound. Or else the pump is shot which is hard to tell unless you put a flowmeter in line with the pressure hose.
You did check the belt tension and condition?.....Mike